Evacuations have begun in areas of the US east coast likely to be hit by Hurricane Earl.
The storm has dropped to category three but is still generating sustained winds of 201km/h (135mph).
President Barack Obama said officials needed to be ready for a "worst case" scenario in a call to the US Federal Emergency Management Agency (Fema).
One island in North Carolina's Outer Banks is being evacuated and visitors are being asked to leave another.
The narrow islands are served by a single main road and officials worry that waves washing over it will cause danger to travellers.
Fema has warned people along much of the the eastern seaboard of the US to be vigilant and follow official bulletins.
Forecasters at the National Hurricane Center said they expected the hurricane to turn north and then run parallel to the east coast.
"The most important thing for people living in Earl's potential tract to do is to listen to and follow the instructions of their local officials," Fema administrator Craig Fugate said.
BBC News
